Embodiments of the present disclosure are directed to an image processing apparatus and an image processing method.
To convert an interlaced image into a progressive image, referred to hereinbelow as IP conversion, direction adaptive interpolation, also known as edge-directed interpolation, can be used to decrease jagged diagonal lines. In addition, with the development of high precision display devices, the importance of magnification processing to magnify an image has increased, which can magnify the jagged diagonal lines.
Technologies to detect an edge direction in an image based on an image signal have been developed.
When interlaced to progressive (IP) conversion is performed, it is desirable to detect a diagonal direction close to the horizontal direction of an image. When both the vertical and horizontal directions of the image are also magnified, it is desirable to detect a diagonal direction close to the vertical direction. However, the operational cost for detecting edge directions for magnification is at least twice that of a general IP conversion.
A differential operator uses a pixel array, such as a 3×3 or a 5×5 pixel array, around a target pixel. However, this operator may not have sufficient precision to detect an edge direction when the direction of the edge is detected using only the output of a differential operator.
More particularly, when a differential operator uses, e.g., a 3×3 pixel array around a target pixel, the angle of a diagonal line close to the horizontal or vertical direction of an image may not be detected with high precision. In addition, when a differential operator uses, e.g., a 5×5 pixel array around the target pixel, detection precision of the edge direction may be enhanced with respect to a 3×3 pixel array, but there may not be sufficient detecting precision due to surrounding influence when there is a small texture around a thin line in the image.
In addition, when the edge direction is detected using only, e.g., the output of a differential operator, a single direction is detected even when two edges cross each other, e.g., at the peak of a polygon in an image. That is, when the direction of the edge is detected using only the output of a differential operator, the edge direction may be erroneous.